Aroon Indicator
The Aroon indicator measures how many periods have passed since the latest high (Aroon-Up) and low (Aroon-Down) within a look-back window, usually 25. Readings near 100 mean a fresh extreme; Aroon-Up above Aroon-Down suggests an uptrend.
Most indicators ask how far price has moved. Aroon asks a different question: how long ago did price make its last high or low? A market making new highs every few days is trending up; one that hasn't made a new high in weeks is losing steam. This entry explains how Aroon is calculated, how to read it and its oscillator version.
- Category
- Indicators and Tools
- Reading time
- 4 min
- Also called
- Aroon, Aroon Up and Down, Aroon Oscillator
- Updated
Aroon in plain words
Developed by Tushar Chande in 1995, Aroon is designed to show whether a market is trending and how strong the trend is.1
A 25-day Aroon-Up measures the days since the 25-day high, and Aroon-Down the days since the 25-day low, both shown on a 0–100 scale.1
The Aroon Oscillator is simply Aroon-Up minus Aroon-Down.2
How Aroon is calculated, step by step
Choose a period
25 is the classic setting.
Find the last high
Count periods since the highest high in the window.
Aroon-Up
(25 − periods since high) ÷ 25 × 100.
Find the last low
Count periods since the lowest low.
Aroon-Down
(25 − periods since low) ÷ 25 × 100.
Compare the lines
Which is higher shows which side has the edge. See Trend.
Worked examples
Example 1 — A fresh high
Uptrend25-period Aroon. The latest high was 2 days ago; the latest low was 20 days ago.
| Aroon-Up | (25 − 2) ÷ 25 × 100 = 92 |
| Aroon-Down | (25 − 20) ÷ 25 × 100 = 20 |
| Oscillator | 92 − 20 = +72 |
Bulls have the edge when Aroon-Up is above 50 and Aroon-Down is below 50.1
Example 2 — The 50 line
Below 50The last high was 13 days ago.
| Aroon-Up | (25 − 13) ÷ 25 × 100 = 48 |
A reading below 50 means the last high came 13 or more days ago.1
Example 3 — A new downtrend
DowntrendAroon-Down jumps to 100 while Aroon-Up falls to 16.
| Aroon-Down | 100 (new low today) |
| Aroon-Up | 16 |
| Oscillator | 16 − 100 = −84 |
A surge to 100 suggests a trend may be emerging; here it is a downtrend.1
Aroon vs ADX
| Aspect | Aroon | ADX |
|---|---|---|
| Measures | Time since highs and lows | Trend strength from price ranges |
| Direction shown | Yes (Up vs Down) | No (strength only) |
| Range | 0 to 100 | 0 to 100 |
| See also | Aroon Oscillator | Average Directional Index |
How traders use Aroon
Spotting new trends
A jump to 100 flags a possible new trend.
Identifying consolidation
Both lines low means no fresh highs or lows. See Range.
Trend filters
Only trade longs when Aroon-Up leads.
Crossovers
Aroon-Up crossing Aroon-Down as a signal.
Advantages and disadvantages
Advantages
- Unique time-based view of trend.
- Shows both direction and freshness.
- Simple 0–100 scale.
Disadvantages
- Jumps sharply, which can be noisy.
- Lags at the start of trends.
- Crossovers whipsaw in ranges.
Going deeper
Read as far as you need. Each level builds on the one before it.
Time, not price
Beginner
Uses beyond trends
Intermediate
Chartists use Aroon to spot emerging trends, find consolidations, define corrections and anticipate reversals.1
The oscillator
Advanced
Plotting Aroon-Up minus Aroon-Down gives one line between −100 and +100, which is easier to filter but hides which side changed.2
Common mistakes
Trading every crossover
In ranges they flip constantly.
Reading it as price strength
It measures time since extremes.
Ignoring the period
Shorter periods are much noisier.
Using it alone
Confirm with price structure. See Market Structure.
Check your understanding
Test yourself before moving on. Each answer comes with an explanation.
Key points to remember
- Aroon measures time since the latest high and low.
- 25 periods is the classic setting.
- Up above 50 and Down below 50 favours bulls.
- A jump to 100 flags a fresh trend.
- The oscillator is Up minus Down.
Frequently asked questions
What does Aroon mean?
What is a strong Aroon reading?
Is Aroon a leading indicator?
Further learning
- Average Directional Index
Another trend-strength tool.
- Donchian Channels
Also built on period highs and lows.
- Trend
What Aroon tries to identify.
- Range
When both Aroon lines fade.
Sources
This article is written in our own words. The sources below support the specific facts, rules and figures marked with a number in the text. Links open the original publisher’s page.
- StockCharts ChartSchool. Aroon (opens in a new tab) Checked .
- StockCharts ChartSchool. Aroon Oscillator (opens in a new tab) Checked .
Educational content, not financial advice. Examples use hypothetical prices and simplified costs; actual fees, margin rules and regulations vary by broker, market and country. We are not affiliated with any publisher linked above. Last reviewed . Report an error or request a source credit.